Journal of Machinery Manufacture and Reliability最新文献

The influence of wave resonance effects on the production of 1 and 2% chitosan solutions in 1% acetic acid is studied. It has been shown that wave treatment of biopolymer suspensions allows one to reduce the duration of the process of its dissolution from 1–2 days to 10–20 min. The resulting polysaccharide solutions do not contain a gel fraction and do not require filtration before further use. Chitosan solutions obtained by traditional mixing and using wave resonance effects have similar rheological characteristics.

The case of a transverse shear plane with rectilinear adhesion cracks collinear to the X and Y axes, weakened by two doubly periodic circular holes and reinforced fillers, was considered. In the process of solving the problem, the goal is to determine the stress intensity factor at the ends of the cracks. For this purpose, boundary conditions are specified along the contour of the circular holes and filling materials. In this case, the boundary conditions are specified at the edges of the cracks. In the process of solving the problem using functions with complex variables, a system of infinite linear equations is obtained along the contour of the circular holes. On the crack faces, singular integral equations are obtained for the specified boundary conditions. The Gaussian method is used to solve singular integral methods in the system of finite algebraic methods. At the same time, a 3D model was built. It was found that the stresses in the plane in a state of intense deformation have large values at the end of the cracks.

The results of a study of the composition, structure, and properties of high-strength tungsten-free hard alloys based on powders obtained by processing TN20 alloy waste by electroerosive dispersion in water are reported. It is shown that the use of the spark plasma sintering method for the production of hard alloy products from powder obtained by electrical discharge dispersion of the TN20 alloy made it possible to improve the physical and mechanical properties of the tungsten-free hard alloy due to its fine-grained structure, uniform distribution of carbide phases, and the absence of significant pores, cracks, and discontinuities.

The stress–strain state of a semifinished product during volumetric purely plastic bending around a radius under conditions of plane strain has been analyzed. The positions of the neutral layers of stresses and strains, as well as the bending moment, have been evaluated using known relationships.

The issues related to the design features and operating conditions of turbochargers are addressed briefly. In addition to long-established technical solutions, new, more advanced options that are intended for further scientific research and practical application in turbocharger bearings are revealed.

Synthesis of engineering solutions for energy storage systems is of great importance for the development of the economy, where renewable energy sources are becoming more and more in demand. Therefore, research, development, and application of renewable sources constitute one of the most important tasks for environmental protection and creation of perspective transportation and energy systems. To increase efficiency, it is necessary constantly to improve technical solutions and introduce new technologies. The development of energy storage systems, with a special focus on mechanical storage systems, is considered. An advanced morphological approach is used for the analysis. A number of engineering solutions are considered, and a hybrid device combining a hydraulic accumulator and a gravity energy storage system is investigated in detail. Conclusions are drawn about possible applications of the engineering solutions found.

This article presents an analysis of the results of a study on a promising method for producing functionally graded composite materials using “cold” gas dynamic spraying technology. In particular, for the Al–Al₂O₃ composite, the influence of the ceramic component content on the change in the coefficient of thermal linear expansion is determined. The results can be used in the design and creation of materials in thermally loaded components to reduce stresses by adjusting thermal gaps.

For the description of power transmission through drive links, a system of linear first-order differential equations has been applied taking into account the accelerations and rates of changes in stresses under torsional and transverse oscillations. An eighth order vector equation has been derived and solved, including algebraic elements, making it possible to calculate the fluctuations of stresses and motion velocities in any link of the system to a first approximation with the use of an engineering method. For a particular drive, the effect of the inertial properties of the load and the features of resistance torque formation exerted on the dynamic characteristics of the drive has been analyzed.

The requirements for woven electric heaters that provide both a contact thermal effect on a person and obtaining a human response to this effect, which is a novelty, are provided. A comparison of the results obtained using woven electric heaters with heat-generating elements made of steel wire and carbon threads is carried out. The experiments have confirmed the validity of these requirements when producing and using woven electric heaters with heat-generating elements made of materials with different physical properties. The results may be of interest to specialists in the field of thermal physics, electrical engineering, physiology, etc.

The methodology of combined application of acoustic emission diagnostics and vibration diagnostics for monitoring the state of damage of samples made of 17GS1 pipe steel with a combined stress during the development of a dominant crack is considered. In the experiments, the stress concentrator is a transverse weld subjected to local crumbling and a guide scratch to a depth of up to 3 mm across the entire sample width. Such a concentrator simulated the effect of buried reinforcement on the weld when laying a pipeline through a water obstacle.